1. Field of the Invention
The present invention relates to fluorene-based alternating polymers to be used as luminescent materials in manufacturing macromolecular electroluminescence (EL) elements, and relates to EL elements using such fluorene-based alternating polymers as light emitting materials.
2. Description of the Prior Art
Examples of EL elements which have been studied thus far, include inorganic semiconductors such as GaAs which have the advantages of being small in size, require little consumption of electric power, etc., are currently being used as display devices having a small surface area, light emitting diode (LED) lamps, semiconductor lasers, and the like. However, in manufacturing such elements, extremely clean processing is required, and it is difficult to make LEDs of large surface area and it is difficult to obtain blue light having good efficiency. Furthermore, there are inorganic semiconductors having fluorescent ions of metal compounds added thereto, and inorganic EL elements made by dispersing inorganic semiconductors into high molecule compounds, but these cause problems in semiconductor stability not only because they require a high operating voltage but also because they operate under high electric fields.
However, as organic EL materials (Appl. Phys. Lett., 51, p.913 (1987)) and macromolecular EL materials (Nature, 347, p.539 (1990)) capable of overcoming such problems are recently being developed, advances in research in this field are continuing to progress. When voltage is applied to an EL element manufactured by depositing organic dyes (Japanese unexamined (laid-open) patent publications 6-136360 and 7-26254), or by putting macromolecules having a conjugate double bond (Int'l patents WO92/03491 and WO93/14177) between an anode and a cathode, holes from the cathode and electrons from the anode are introduced, move to a luminescent layer and emit light when they recombine thereafter. Currently, efforts are being made to find applications of such EL elements for next generation flat panel color display devices, electrochemical cells, image sensors, photocouplers, and the like which use LEDs, which will replace cathode-ray tubes, gas plasma displays, liquid crystal displays used at present. Elements manufactured by deposition of organic dyes have problems in reproducibility and in making uniform films, and macromolecule-based elements have overcome such problems to a certain degree, but improved stability, efficiency and durability are still required for desired applications to practical commercial use. Poly(phenylene vinylene) (PPV), polythiophene (PTh) and polyphenylene-based macromolecules (Synth. Met. 50(1-3), p.491 (1992) and Adv. Mater., 4, p. 36 (1992)), are known as representative macromolecular luminescent materials which have been studied up to now, but these materials have the disadvantage that the final material is insoluble in any organic solvent. The processing suitability is improved by introducing appropriate substituents and PPV or PTh derivatives (Synth. Met., 62, p.35 (1994), Adv. Mater., 4, p.36 (1994), and Macromolecules, 28, p. 7525 (1995)) which emit diverse lights of blue, green and red colors are known but the manufacturing process of such derivatives is very complicated, and there are also problems in stability. Moreover, fluorene-based macromolecules which emit blue light (Jpn. J. Appl. Phys., 30, p.L1941 (1991)) have been reported but these have disadvantages in that they can not exhibit various other colors, and require the use of materials and manufacturing methods from which macromolecules with more diversified conjugate double bonds can not be made. The inventors of this application discloses a fluorene-based alternating polymer element for an electroluminescence device having a conjugate double bond, which overcome the above-described problems, in Korean Patent No. 16449 on May 16, 1996.
Meanwhile, the phenyl group macromolecular containing an acetylene group is disclosed in Makromol Chem. 191, p. 857 (1990), Macromoleculars, 27, p 562 (1994), J. Chem. Soc., Chem. Commun., p 1433, (1995) and Macromolecules, 29, p 5157 (1996), which are related concerning a non-linear optical material, an optical conductivity, and a photoluminescence (hereinafter, called PL).